Patent GB-968079-A (GB)
Title: Polyurethane elastomers
IPC: C08L75/00
Filed: 1960-11-17
Abstract: 968,079. Polyurethanes. GOODYEAR TIRE & RUBBER CO. Nov. 17, 1960 [May 23, 1960], No. 39488/60. Heading C3R. The invention comprises a polyurethane elastomer which is the reaction product of (1) a primary or secondary diamine with (2) a bis chloroformate of a polyether glycol, the polyether glycol having a hydrophobic backbone, composed essentially of repeating polymethyleneoxy groups in which the number of methylene groups between the ether oxygen is at least 3 and in at least the majority of which is at least 4 to which at least one of the hydroxyls of the glycol is connected by a hydrophilic group. The elastomer can be prepared by aqueous interfacial phase extension of the bischloroformate and the diamine using at least 1¢ to 4¢ mols of the diamine for each mol of the bis chloroformate, usually in the presence of a base to neutralize the liberated hydrogen chloride. Dispersion of the aqueous diamine and the bischloroformate is aided by addition of emulsifiers such as alkali metal organic sulphonates and fatty acid soaps and tallates. By the term "hydrophilic group" is meant that that the group contains an -O-(CH 2 )ygroup adjacent and connected to one of the hydroxyls where y is an integer from 1 to 3 inclusive. The polyether glycol is composed primarily of polymethyleneoxy hydrophobic groups -O[(CH 2 )n-O] where x is the number of groups in the "hydrophobic backbone", x is of a magnitude sufficient to give a polyether glycol of molecular weight 700 to 6000 and n is the number of methylene groups between adjacent ether oxygens. The polyether glycols can be produced by polymerization of the appropriate alkylene oxide (e.g. tetra-hydrofuran) in the presence of a Lewis acid catalyst and an initiator capable of yielding a hydrophilic group, the catalyst being added before the initiator and in quantities to give an excess of catalyst over initiator and the initiator being used in an amount of 1 to 5.5 mols per mol of polymer to be produced, the polymer/catalyst complex then being hydrolysed. Other oxides can be used with the tetrahydrofuran. Alkylene ethers, such as epoxy octylene ether, allyl glycidyl ether and glycidyl vinyl ether can be included, to give unsaturated products. The latices of polyurethane obtained or the coagulated elastomers can be compounded with carbon black, processing oils, silica, metal oxides and plasticizers. In examples (1) a polyether glycol obtained by the above method from tetra-hydrofuran and ethylene oxide with a boron trifluoride catalyst is reacted with phosgene to give the bis-chloro-formate. This is added slowly to an aqueous mixture containing sodium hydroxide, sodium lauryl sulphonate and two molecular proportions of piperazine. The resulting latex coagulates on boiling and the elastomer is filtered off; (2) a similar process is applied to an unsaturated polyether obtained from tetrahydrofuran, ethylene oxide and allyl glycidyl ether. Quinone or other antioxidants may be present to give an elastomer free from gel, (3) for comparison the polyether was prepared by adding allyl glycidyl ether to the tetrahydrofuran before the boron trifluoride and ethylene oxide. The elastomer obtained has lower dilute solutionviscosity; (4) trimethylene oxide is used as hydrophilic initiator. In other similar examples the polyether used is prepared from (5) tetrahydrofuran, ethylene oxide, allyl glycidyl ether and propylene oxide; (6) and (7) tetrahydrofuran, ethylene oxide, allyl glycidyl ether and (6) mixed butylene oxide-1, 2 and -1, 3, (7) 1,2- and 2,3- epoxy-octane; (8) and (9) tetrahydrofuran, ethylene oxide and allyl glycidyl ether using (8 antimony pentachloride and (9) mixed ferric chloride and thionyl chlorides as catalysts. In Examples (11) and (12) the diamines used in place of piperazine are cis- and trans-dimethyl piperazine, ethylpiperazine, N,N 1-diphenyl -pphenylene diamine, dihydro-5, 6-phenazine, N, N 1-dimethyl-diaminoethane, and ethylene diamine. Specifications 815,122 and 965,764 are referred to.